<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title></title>
    <style>
    div {
      height: 100px;
      border: 5px solid blue;
      border-radius: 50px;
    }
    .red {
      width: 100px;
    }
    .orange {
      width: 200px;
      line-height: 100px;
      text-align: center;
    }
    </style>
    <link href="css/style.css" rel="stylesheet">
  </head>
  <body>
  <div class="red"></div>
  <div class="orange">高度一半或50%</div>
  </body>
</html>
